First look: Jamis Dakar Sixfifty B

Full suspension with a new/old twist

The 2010 Jamis Dakar Sixfifty B series, designed around the emerging 27.5-inch (650B) wheel standard, is modeled on the New Jersey company's XCT mp³ multi-link full-suspension platform.

BikeRadar got the lowdown on the prototype at the 2009 Sea Otter Classic in April.

Jamis will offer two models, the US$4,575 B2 and the US$2,875 B1, designed to keep a low center of gravity and include 10mm shock hardware for increased lateral and torsional stiffness and enhanced rear shock durability and performance.

"The benefit of a 650B wheel size is that you get the best of both the 26-inch and 29er worlds without the negatives of each," said Jamis MTB product manager Craig Hoyt. "650B wheels offer almost all the lightweight, acceleration and flick-ability assets of a 26-inch wheel while delivering the great 'roll over' attributes of a 29er wheel without the weight penalty."

The 27.5-inch wheel size is not new. Early mountain bikes from the late 1970s, early '80s used the wheel size, based on French wheel diameters from the 1940s and `50s, when off-road bikes were called 'campers' or 'woodsies'. When mass mountain bike production kicked in, 26-inch wheels became the standard. The larger 29-inch/700c size took hold in the mid to late 1990s, and a resurgence of the middle-cousin 27.5/650B size is slowly taking shape.

For the Dakar B series, Jamis chose the White Brother's 130mm travel Fluid fork with linear air spring, which features a 20mm thru-axle for stiffness and security, a full open oil bath damper, 32mm stanchions, a reinforced steer tube and beefed-up crown. Hoyt chose the fork for its air pressure, compression and rebound damping adjustability as well.

2010 Jamis Dakar Sixfifty B2

  • Frame:  Kinesium aluminium alloy main triangle, weight-optimized 7005 seat and chainstays, mp3 linkage design, cartridge bearing pivots, 10mm hardware, replaceable derailleur hanger
  • Fork: White Brothers Fluid 650B-130 with 20mm front axle, 32mm stanchions, open bath damping, external compression and rebound adjustors, 130mm travel
  • Rear Shock: RockShox Monarch 3.1   
  • Headset: FSA ZS3, semi-integrated with 20mm shim stack, 1-1/8”
  • Wheels: American Classic 650B XC disc wheels, AC 20mm thru-axle front and AC225 rear hubs
  • Tyres: Kenda Nevegal 650B 120tpi, 2.35 front, 2.1 rear, folding
  • Derailleurs: SRAM X.0 mid-cage rear and X.9 34.9mm top pull front
  • Shifters: SRAM X.0 trigger with Matchmaker clamp, 27-speed
  • Chain: SRAM PowerChain 971 with Gold Power-Link
  • Cassette: SRAM PowerGlide 950 , 9-speed, 11-34T
  • Crankset: TruVativ Noir XC 3.3, 44/32/22T, 175mm length
  • Bottom Bracket: TruVativ Giga X Pipe TEAM
  • Brakeset: Avid Elixir CR hydraulic disc brakes, with Matchmaker clamp, 180mm front/160mm rear rotors
  • Handlebar: Ritchey Mountain Pro Rizer, 31.8mm clamp/ 670mm wide
  • Stem: Ritchey Pro 4-Axis 44, 31.8mm clamp x 6-degree rise
  • Grips: Jamis Lock-On, dual density
  • Seatpost: Crankbrothers Joplin post with remote, 31.6mm diameter x 350mm length
  • Saddle: Syncros FL, Ti Hollow rails
  • Sizes: 13”, 15”, 17”, 19”, and 21”
  • Colour: Anodised Black
  • Price: US$4,575

2010 Jamis Dakar Sixfifty B1

  • Frame: Kinesium aluminium alloy main triangle, STW weight-optimized 7005 seat and chainstays, mp3 linkage design, cartridge bearing pivots, replaceable derailleur hanger
  • Fork White Brothers Fluid 650B-130 with 20mm front axle, 32mm stanchions, open bath damping, external compression & rebound adjustors, 130mm travel
  • Rear Shock: RockShox Ario shock, 10mm hardware   
  • Headset: FSA ZS-3 Zero stack semi-integrated, 1-1/8"
  • Wheels: WTB LaserDisc Trail 650B, 32H, eyeletted, with Formula 20mm thru-axle sealed bearing front and Shimano Deore 6-bolt rear disc hubs, DT Swiss Champion 2.0mm stainless steel spokes and nickel-plated brass nipples
  • Tyres: Kenda Nevegal 650B 60tpi, 2.35 front, 2.1 rear, Wire bead
  • Derailleurs: Shimano Deore XT Shadow rear and Deore 34.9mm top pull front Shifters: Shimano SLX Rapidfire Plus-SL, 27-speed
  • Chain: SRAM PowerChain 971 with Gold Power-Link
  • Cassette: SRAM Powerglide 950, 9-speed, 11-34T
  • Crankset: Shimano M521 Hollowtech, 44/32/22T, 170mm length
  • Bottom Bracket: Shimano ES25, Octalink, 73 X 121mm
  • Brakeset: Hayes Stroker Ryde hydraulic disc brakes with V6 rotors
  • Handlebar: Ritchey Mountain Comp Rizer, 31.8mm clamp x 20mm rise x 670mm Stem: Ritchey Comp OS, 31.8mm clamp x 6-degree rise
  • Grips: Jamis Lock-On, dual density
  • Seatpost: Ritchey 2B OS, 31.6mm diameter x 350mm length, with alloy clamp  cromoly seatpin
  • Saddle: WTB Rocket V Comp with SL top
  • Sizes: 13”, 15”, 17”, 19”, and 21”
  • Colour: Metallic Mash
  • Price: US$2,875

Look for a ride review following the 2009 Interbike Outdoor Demo in late September.

For more information, visit www.jamisbikes.com.

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